Effects of dicumyl peroxide on cell formation of biopolymer blend-activated carbon composite foams

Abstract

Immiscible biopolymer blends of polylactic acid (PLA) and polybutylene succinate (PBS) with a weight ratio of 80/20 were compatibilized by different concentrations (0, 0.1, 0.3 and 0.5 parts per hundred resin (phr)) of dicumyl peroxide (DCP) in the presence of 3 phr of activated carbon (AC). Influences of DCP on the melt rheology at foaming temperature, cell formation and morphology and foam properties of PLA-PBS-AC composites using 5 phr of azodicarbonamide (ADC) as a blowing agent were reported. It was found that the melt viscosity, relating to the melt flow index (MFI) of PLA-PBS-AC composite foams increased with increasing DCP loadings due to more compatibility between PLA and PBS. Closed cells with thick cell walls were obtained with the addition of DCP. Also, the cell size and cell density tended to decrease by DCP adding since lower cell expansion and coalescence occurred at higher polymer surface tension. The crystallinity (Xc) and thermal properties of PLA and PBS in composite foams were almost unchanged when DCP was filled in the system. The PLA-PBS-AC composite foam having 0.3 phr of DCP provided the lowest foam density (pf) and the highest void fraction (Vf) of 0.5766 g cm3 and 54% respectively.